Underground Installation below Div 2 Area

[nhee]

Does the NEC specify the below-grade areas beneath Class 1, Div 2 hazardous locations as hazardous areas? I thought that it did, but now I cannot locate a section that indicates this.

Application is an UG conduit that goes from non-haz. location to non-haz location, but passes below a Div 2 area. I'm trying to determine if PVC (non-concrete encased) is allowable. The above-grade hazardous area is created by a high pressure Natural Gas flanged connection, so this should not be a case of flammable liquids leaking into the ground and into the conduit. I am thinking that a PVC conduit would be acceptable.

 

[rbalex]

Re: Underground Installation below Div 2 Area

The NEC does not make it a general requirement; however, it does specify the underground wiring methods below SOME Division 1 and 2 locations. In fact, revisions in the 2005 NEC Art 514 clarified the area below Division 1 is not classified; nevertheless the wiring method is still called out in 514.8 ? but see the exception.

As for the application you have specified, no special requirements are necessary as long as both ends of the conduit run terminate in unclassified locations.

You may find my Proposal for Section 501.15(B)(2) interesting. (It must be great-no one commented on it - although I plan a few adjustments to the aboveground, open-air part)